晚疫病过敏反应阻断突变体抗氧化酶与相关基因的变化分析

马铃薯抗晚疫病基因R3a和Avr3a互作符合基因对基因假说.为了解R3a和Avr3a基因互作后过敏反应(HR反应)发生机制,本实验利用一个在番茄中构建的MM-R3a-Avr3a系统,以两份筛选到的HR反应被阻断的突变体为材料,研究它们在喷施诱导剂地塞米松(DEX)诱导Avr3a基因表达后活性氧爆发、活性氧清除酶和抗氧化基因的变化情况.结果显示:MM-R3a-Avr3a在DEX处理后有O2-产生和H2O2累积并产生整株的HR反应并导致植株死亡,在突变体中也有O2-产生和H2O2累积却没有导致细胞死亡,说明突变基因与HR反应的发生关系密切;DEX处理后抗氧化酶基因SOD、PPO、CAT在转基因番茄MM-R3a-Avr3a和突变体中的变化有明显差异,由此推测番茄突变体中关键基因的突变导致活性氧清除酶和相关基因的表达发生变化.该研究为探索HR反应的发生机制及了解晚疫病抗病基因抗病机理的打下基础.

Analysis the Changes of Antioxidant Enzymes and Relevant Genes in Late Blight Resistant Hypersensitive Response Blocked Mutants

The interactions of late blight resistant gene R3a from potato and Avr3a from Phytophthora infestans suit to the gene-for-gene model. In order to further discovery the mechanism of R3a and Avr3a gene interactions and hypersensitive response（HR）,an inducible system in tomato was constructed,named MM-R3a-Avr3a,to screen HR interrupt mutants in previous study. In this study two mutants and wild MM-R3a-Avr3a as materials were used to study the changes of reactive oxygen species,the activity of anti-oxidant enzyme and antioxidant genes after treatment with the inducer Dexamethasone（DEX）. The results showed that after the treatment with DEX, O2-and H2O2 were produced within 2 hours in MM-R3a-Avr3a. Interestingly,the mutant also detected the accumula-tion of O2-and H2O2 but didn’t produce HR. The results demonstrated the mutant genes had a close relationship with HR. The expression of SOD,PPO,CAT genes and activity of POD,CAT,APX had significantly changes between MM-R3a-Avr3a and the mutants. The results indicated that the mutation in tomato changed the active oxygen scavenging enzymes and genes. This study would provide the basis to explore the mechanism of HR reactions and late blight resistance.